Pre-stressed rolling mill



April15,fl 9 6 9 D. m. ELTON 3,438,235

FEE-STRESSED ROLLING MILL FiledSepc. 15.1966 Sheet of 4 Y Inventor,DEREK ARTHUR LMBERT ELTON April 15, 1969 D. A. EL ON IPRESTRESSEDROLLINGMILL Filed Sept. 15. "1966 I sheet 2 0M I nvenlor A ril 15, 1969 I V D.A. 1.. ELTON 3,438,235

FEE-STRESSED ROLLING MILL v Filed Sept. 15 1966 Sheet om I n venlorDEREK ARTHUR LAMBERT ELTON April 15,1969

FEE-STRESSED ROLLING MILL Filed Sept. 15, 1966 Sheet 4 of 4 InvenlorDEREK ARTHUR LAMBERT ELTON D. A. I... ELTON 3,438,235

United States Patent 3,438,235 PRE-STRESSED ROLLING MILL Derek A. L.Elton, Poole, Dorset, England, assignor to Loewy Robertson EngineeringCompany Limited, Bournemouth, England, a corporation of Great BritainFiled Sept. 15, 1966, Ser. No. 579.557 Claims priority, applicationGreat Britain, Sept. 17, 1965, 39,866/ 65 Int. Cl. B21!) 31/20, 31/24US. Cl. 7-2240 4 Claims ABSTRACT OF THE DISCLOSURE This inventionrelates to rolling mills in which the rollbearing chocks of one of twosuperposed rolls are supported on the bearing chocks of the other rollby spacing means. The spacing means may be arranged between the chocksof either the working rolls or the back-up rolls of the mill, ifprovided, and they may be adjustable so that the distance between theserolls, and thereby the rollpass opening, can be varied.

In one mill of this type, the spacing means between the rolls chocks areformed by relatively slender screw spindles threaded at one end into thechocks of -a mill roll and resting with their other ends on the chocksof another roll, with the roll-pass opening between both rolls. A rotarydrive is provided for the spindles, whereby the chocks of the first rollcan be lifted or lowered as required when the setting of the roll-passopening has to be changed. This design has been adopted for rollingmills whose housings are pre-stressed, e.g., by hydraulic means.

It has been found that in such mills, the pre-set rollpass opening canbe kept constant throughout rolling and a rolled article of uniformthickness produced only if the adverse influence of elastic deformationswhich are bound to occur during rolling in the rolls and in their chocksare eliminated or at least greatly reduced. To this end, the load on thespacing means during rolling is measured by load-meters, and the outputof these load-meters fed into electric control circuits which vary thepre-stressing force in such a manner that the desired result isobtained, as described in the British Patent No. 955,124, the loadmetersthere being formed by cells which are in contact with screw spindlesacting as spacing means for the chocks. It is essential for exactmeasurement of the loads and effective control of the pre-stressingforce that close contact be maintained between the spindles and theloadmeters throughout rolling.

It is an object of the present invention to provide a rolling mill whichis equipped with conventional screwdown means for the adjustment of theroll-pass opening, and also with the afore-described arrangement ofchockspacing means, so that load-meters may be used in the mannerdescribed above for the control of a pre-stressing force.

According to the present invention, a rolling mill having screwdownmeans arranged between the mill houslugs and the chocks of a roll forthe adjustment of the 3,438,235 Patented Apr. 15, 1969 "ice pass-openingbetween said roll and another roll, spacing means in the form of screwspindles threaded into these chocks and resting on the chocks of theother roll, and a drive for said screwdown means, is provided withmovement-reversing means between the screwdown means and said spacingmeans, whereby the chocks of the first roll and these spacing means aredisplaced by the same distance but in opposite directions, so that thespacing means remain stationary relative to the chocks of the secondroll during displacement of the chocks of the first roll by thescrewdown means. Thus, in the case of loadmeters being placed betweensaid spindles and the chocks of said second roll, the contact betweenthe spindles forming the chock-spacing means and the load-meters willnot be affected in any way by the displacement of the chocks of thefirst roll during adjustment of the roll-pass openmg.

The mill according to the invention may be provided with pre-stressingmeans for the housings and the prestressing force be controlled by theload-meters so as to eliminate or greatly reduce the adverse influenceof elastic deformations of the chocks or rolls on the setting of theroll-pass opening as described in the British Patent No. 955,164.

In a preferred embodiment of the invention, the screwdown means and thechock-spacing means are drivably connected to each other by a set ofreversing gears which, upon the chocks of the first roll being loweredby the screwdown means, raises the spindles relative to said chocks bythe same distance, and vice versa, so that the position of the spindlesin space remains unaltered.

The screwdown means may be of any known design and may consist of heavyrotary spindles threaded into the housings and resting on the top of anupper or the bottom of a lower roll. Alternatively, the spindles may bescrewed into wedges acting on the chocks, so that upon rotation of thespindles, the chocks are lifted or lowered. In either case, the settingof the roll-pass opening is effected by the spindles of the screwdownmeans.

The screwdown means and the chock-spacing means may be driven by thesame motor or motors and a reduction gear provided between the motor ormotors and either means. The reversing gear provided according to theinvention may then be combined with that reduction gear.

Alternatively, the screwdown means and the spacing means may be drivenfrom separate motors, the motors being automatically controlled so thatthey start and stop simultaneously, the drives of the motors being solaid out that the chocks and spacing means are moved by the samedistance, but in opposite directions.

The mill according to the invention may have either working rolls onlyor working rolls supported by backup rolls, and the screwdown means andthe spacing means may accordingly act either on the chocks of workingrolls or of the back-up rolls.

Several embodiments of the invention will now be de scribed by way ofexample with reference to the accompanying drawings, in which:

FIG. 1 is a side elevation of a rolling mill according to the invention,partly in section, along the line I-I of FIG. 4. 1

FIG. 2 is a side elevation, again partly in section, along the line11-11 of FIG. 5.

FIG. 3 is a section along line III-III of FIG. 2.

FIG. 4 is a section through the rolling mill of FIG. 1 along the lineIVIV of FIG. 1.

FIG. 5 is a section through the rolling mill of FIG. 2 along the lineV-V of FIG. 2.

The rolling mill shown in FIGS. 1 and 4 comprises a base 2 and twohousings 4, of which only one is shown,

each housing having a window 6. Two roll-assemblies are mounted in thehousings, each assembly comprising a working roll 8 mounted at its endin bearings 9 supported in chocks 10, and a backing roll 12 mounted atits ends in bearings 13 supported in chocks 14. The upper chocks 14 arespaced apart from the lower chocks 14 by supports 16 in the form ofscrew spindles threaded into recesses 18 formed in the lower part ofeach of the upper chocks 14, the lower ends of the supports abuttingagainst pressure pads 20. A load meter 22 in the form of a load cell isinserted between each pressure pad and the top of the lower chocks 14.The pads and the load meters are accommodated together in recesses 23formed in the upper part of the lower chocks 14. Plungers 24displaceable in hydraulic cylinders 25 are arranged between the chocks10 of the upper working roll and those of the lower working roll wherebythese two rolls are maintained in contact with their respective backingrolls 12.

Each of the lower chocks 14 is mounted on a thrust block 26 in which ahydraulic cylinder 28 is formed, the cylinders being displaceable overrams 30 secured to the lower wall of the windows 6. The pressure of thehydraulic fluid in the cylinders 28 acts both on the upper and the lowerparts of the housings 4, whereby the latter are pre-stressed.

The mill so far described is similar to that of British Patent 955,164,the output of the load meters 22 being utilised for controlling thepre-stressing forces in such a manner that the load taken by thesupports 16 remains constant during a rolling operation. However,whereas in the mill according to the above-mentioned patent adjustmentof the roll-pass opening is effected exclusively by the screw spindleswhich act as supports for the upper roll assembly, no other roll-passadjusting means being provided in the earlier mill, the rolling millaccording to FIGS. 1 and 4 of the present invention is provided withroll-pass adjusting means in the form of screwdown spindles which passthrough the upper parts of the housings 4 and bear with their lower endsagainst the upper chocks 14. Each spindle 32 is threaded into a bush 34secured to a housing 4, for instance, by a retaining ring 35. Thespindle 32 has further a smooth upward extension 36 which is slidablykeyed at 37 to a worm wheel 38. The latter is driven by a worm 40 from amotor, not shown.

As will be clear from the foregoing, the upwardly directed pressureproduced in the hydraulic cylinders 28 is taken partly by the spindles16 and partly by the rollassemblies 10, 12, the two pressure componentsbeing transmitted to the upper chocks 14 and from there through thespindles 32 to the upper parts of the housing 4. During a rollingoperation, the load on the spindles 16 is therefore the differencebetween the pre-stressing force and the roll-separating force, as isalso the case with the rolling mill according to British Patent No.966,164. I

In the rolling mill according to FIGS. 1 and 4, the adjustment of theroll-pass opening is effected in a well known manner by the screwdownspindles 32 which lower or raise the upper chocks 14 by the requiredamounts. In order to maintain the spindles 16 in contact with the pads20 during a rolling operation, irrespective of any adjustments of theroll-pass opening, the spindles 16 are raised relative to the upperchocks 14 by the same distance as that by which these chocks are movedtowards the lower chocks 14; conversely, the spindles 16 are loweredrelative to the upper chocks 14 by the same distance as the latterchocks are moved away from the lower chocks 14. To this end, the worms40 are integral with or secured to spur gears 42 which are in mesh withpinions provided on shafts 48 which extend freely from the upper partsof the housings 4 and are connected to upward extensions 44 of thespindles 16. The connection is effected by means of links 46 pivoted tothe shafts 48 and extensions 44 by pins 47, whereby assembly anddismantling of the spindles 16 from the shafts 48 is facilitated.

The threads on the spindles 32 and 16 and the ratio of reduction of thegear drive between the two spindles are so selected that the spindles 16move by the same distance relative to the upper chocks 14 as thesechocks are displaced in the opposite direction by the spindles 32. Thus,the spindles 16 remain stationary in space and the contact between thespindles 16 and the pressure pads 20 is not affected by the movement ofthe upper chocks 14.

The rolling mill shown in FIGS. 2, 3 and 5 is to some extent identicalwith that of FIGS. 1 and 4, and corresponding parts have been marked inFIGS. 2, 3 and 5 with the same reference numbers as have been used inFIGS. 1 and 4, increased by 1. The mill of FIGS. 2, 3 and 5 hasaccordingly two housings 104 with windows 106, working rolls 108 withbearings 109 and chocks 110, backing rolls 112 with bearings 113 andchocks 114, supports 116 in the form of threaded spindles, pressure pads120 and load cells 122, all arranged as described with respect to therolling mill of FIGS. 1 and 4. Screwdown spindles 132 are threaded intosleeves 134, the latter being housed in recesses of the upper back-upchocks 114. The sleeves are formed at their outsides with worm teeth forrotation by worms 140 (FIGS. 3 and 5) and are prevented from axialmovement with respect to the upper chocks 114 by retaining rings 60.Rotation of the screwdown spindles 132 is prevented by keys 61 which areslidable in grooves 62 in the upper chocks 114. Rotation of the sleeves134 will therefore cause vertical displacement of the spindles 132 andthereby also of the upper roll assembly.

As shown in FIG. 2, the spindles 132 abut against the upper ends of thewindows 106.

The drive of the spindles 132 is here combined with the drive for thespindles 116, as will now be described in more detail with reference toFIG. 3. The horizontal shaft 64 supported on the upper part of upperchock 114- carries a helical gear wheel 66 which drives a pinion gearwheel 67 on a stub shaft 68. A worm 70 mounted on shaft 68 drives a wormwheel 72 mounted on the upper extension of one of the spindles 116.Rotation of shaft 68 is transmitted through bevel gears 74, shaft 75 andbevel gears 76 to another stub shaft 78 which latter has a worm 80driving a worm wheel 82 mounted on the upper extension of the otherspindle 116. Both spindles 116 can therefore move together.

The shaft 75 carries also the afore-mentioned worm 140 which drivessleeve 134. The threads on the spindles 132 and 116 and their ratio ofrotation is so selected that the spindles 116 move by the same amountrelative to the upper chocks 114 as these chocks are displaced in theopposite direction by the spindles 132. Here again, the spindles 116will remain stationary in space irrespective of any movement of theupper chocks 114 for rollpass adjustment purposes, so that the contactbetween the spindles 116 and the pads 120 remains unaffected.

In an alternative embodiment (not shown) the shaft 64 is extended as faras the second stub shaft 78 and provided with a further set of gearwheels for driving the second stub shaft. The worm can then be arrangedbetween the two sets of gear wheels. This makes the shaft 75 and thegear wheels 74, 76 unnecessary.

The shaft 64 may be driven through articulated spindles (not shown) froman electric motor.

As will be clear from FIGS. 4 and 5, the arrangement shown in FIGS. 1, 2and 3 is duplicated in respect of each housing. A separate motor may beprovided for driving the screwdown spindles in each housing, and meansmay be provided for synchronizing the speed of each motor so that thespindles of both housings move by equal distances. For this purpose, theoutput shafts of both motors may be connected, if desired, by a clutch.

The provision of screwdown means makes it possible to displace the upperroll assembly relative to the lower roll assembly by any desireddistance, so that the mill according to the invention can be used forreducing relatively thick rolled articles, such as slabs or plates. Atthe same time, it is possible with the mill according to the inventionto effect accurate control of the pre-stressing force as described inBritish Patent No. 955,164 and in British application No. 245 19/ 63.

I claim:

1. A rolling mill having housings, rolls mounted in said housings,chocks for mounting said rolls in said housings, screwdown meansarranged between said housings, and said chocks for the adjustment ofthe pass-opening between said rolls, spacing means in the form of screwspindles threaded into these chocks and resting on the chocks of theother roll, a drive for said screwdown means and movement-reversingmeans between said screwdown means and said spacing means, whereby thechocks of the first roll and these spacing means are displaced by thesame distance but in opposite directions, so that the spacing meansremain stationary relative to the chocks of the second roll duringdisplacement of the chocks of the first roll by the screwdown means.

2. A rolling mill according to claim 1, in which the movement-reversingmeans consist of reversing gears which drivably connect to each otherthe screwdown means and the chock-spacing means and which upon thechocks of one of the mill rolls being lowered by the screwdown meansrelative to the chocks of another roll, raise the chock-spacing meansrelative to the chocks of the first roll by the same distance as thesechocks have been lowered, and vice versa.

3. A rolling mill according to claim 2, in which the reversing gear isarranged between the screwdown means and the chock-spacing means anddrivably connected to both.

4. A rolling mill according to claim 2, in which the reversing gear isdrivably connected to a reduction gear arranged in the drive of thescrewdown means.

References Cited UNITED STATES PATENTS 3,345,848 10/1967 Henschker72-237 FOREIGN PATENTS 955,164 4/ 1964 Great Britain.

RICHARD J. HERBST, Primaly Examiner.

B. T. MUSTAIKIS, Assistant Examiner.

U.S. Cl. X.R. 72248

